There was rioting and looting in the Civil Rights Movement, and progress was still made. The situation with Gandhi is also much more complicated than commonly presented. I haven't read enough to know if a true cause-and-effect relationship between rioting and looting and progress or lack of progress, but I know, just from my position as a white person, that white people should check themselves before criticizing the rioting and looting, because they don't understand what it's like to be a POC dealing with, like St Martin said, the distrust, the body count, and so on.
That said, I wouldn't take rioting and looting as a sound political strategy, nor is it called for by any of the major organizations holding protests. It scares a great number of white people, still the majority, obviously, to retreat further into their white privilege bubble and start embracing the law and order politics by which, I think, they'd otherwise be repulsed (as they stand...I like actual law and order that serves everyone, but we know that's not the "law and order" the privileged majority culture understands). I think fear is a great motivator of the majority culture in any country, just look at India with Modi, Russia with Putin, China and their Party, but it is clearly effective in the States at motivating a population of white people to vote in a horror show that somehow makes them feel safe and secure. He lost the popular vote, but won the white vote 58% to 37%. Thing is, you can't just tell people not to riot and loot, so you either accept that it happens sometimes as a result of injustice and make sure property owners are made whole, or you go with the fascist police state option, gas and blast peaceful protesters and, who knows, invoke the Insurrection Act or otherwise find some justification for deploying the military to quell the protests.
I didn't like the direction our country was headed in 2016, and I'm very, very worried about it now. I think most of us think that America could never be a fascist dictatorship, but our democracy is clearly not safeguarded sufficiently to prevent the suppression of free speech or electing a president with the second-most votes. I think we need a new Constitution that reflects the reality of a post-industrial, information-based country. (BTW, save all the gun toting, which I think should be totally illegal and felonious, I found some empathy for the anti-quarantine/lockdown activists and protesters. I disagree with them, but I get it. A sticky issue is: Where do your rights to protest end and the interest of the public health begin?)
I also think we need to take care of reparations for Black and indigenous people.
Thank you for letting me get all of that off my chest.